Patients with upper extremity paralysis due to spinal cord injury have been able to regain limited function of their hand through the use of an implanted neuroprosthesis called the Freehand System. The system is configured volitionally moving the shoulder. This motion is detected by an externally mounted position sensor, which sends a signal to the control unit of the system. Such a control system requires the patient to retain some volitional control of their shoulder muscles, thus limiting use of the system to patients with higher levels of spinal cord injury, a new control scheme is needed. The purpose of this research is to investigate the feasibility of using myoelectric signals as the control source for a hand-grasp neuroprosthesis. With the proposed scheme, control signals will be derived from weak volitional myoelectric activity, making it possible for patients without sufficient shoulder mobility to use the neuroprosthesis. The focus of this research will be on obtaining command signals that allow proportional control of the neuroprosthesis. Percutaneous intramuscular electrodes will be used to record myoelectric activity from muscles that are appropriate for use as control sources. The degree of control of the myoelectric signal that the subject has will be evaluated.